#define _CRT_SECURE_NO_WARNINGS 1

https://leetcode.cn/problems/maximum-depth-of-binary-tree/


/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    int maxDepth(TreeNode* root) {

        queue<TreeNode*> que;

        if (root != NULL)   que.push(root);

        int depth = 0;
        while (!que.empty())
        {
            int size = que.size();

            while (size--)
            {
                TreeNode* temp = que.front();
                que.pop();

                if (temp->left != NULL)   que.push(temp->left);
                if (temp->right != NULL)  que.push(temp->right);
            }
            depth++;
        }
        return depth;
    }
};